AC ISNT COOLING

I bought this car in March of 2006 and initially it was fine. After a few months the AC stopped cooling. I would put coolant in it and it would be perfect for a couple days but then the coolant would leak out and it would stop blowing cold. I dealt with that for a couple years until this April when I got it looked at by an AC guy. I was told to replace the coolant hoses (the high pressure hose and the suction hose) in the engine. I did so myself and I had no problems with the replacement. Everything worked great until very recently when it stopped cooling during a road trip. I added freon again but it only took half the can and never started cooling the car. The compressor kicked on like it should have but it still won't cool. The system blows and heats normally but no cold air and that's important here in Florida. Any ideas?